Camera phones came into widespread use in the early 2000s. Initially their digital image quality was low compared to dedicated-purpose cameras. Since then, they have made continual progress in terms of resolution and image quality. The advent of smartphones was accompanied by significant increases in computer processing power of mobile units (cellular telephone handsets). The increased processing power also carried over into tablet computers that evolved from smartphones. With much improved camera quality and powerful microprocessors, smartphones and tablets have lately eclipsed dedicated-purpose consumer-grade digital cameras in terms of popularity.
One popular use of tablets and smartphones is accessing social networks such as Facebook, Google+, LinkedIn, and Orkut. Having a single device with network access, abundant memory, fast microprocessors, and a good quality digital camera has fostered a popular trend in which people capture large numbers of pictures and quickly post them on social networks. The days of judiciously making use of 24 or 36 film exposures are history. The user interfaces in smartphones and tablets emphasize ease of use. The camera control software (‘app’) in smartphones and tablets has few manual settings and users expect to be able to simply touch a virtual shutter release button to rapidly capture a succession of good quality images.
Cameras, including those in smartphones and tablets, are often used to take group photos. A group often includes persons at significantly varying distances. Certain digital cameras are designed to detect faces and adjust the focus based on one or more of the faces. If the faces are at varying distances, however, all of the faces cannot be focused in the image if the camera has a relatively large fixed aperture. One face may be selected for focusing or a compromise may be made in focusing, but there would no guarantee that a particular person's face would be well focused.